Orientation system for a subsea well

ABSTRACT

An outer wellhead housing has an external locator member initially oriented in a desired direction. An inner wellhead housing lands in the outer wellhead housing. A BOP orientation spool with an external orientation member and an internal orientation member lands on the inner wellhead housing and orients via the external locator member. A tubing hanger with an orientation member and associated tubing hanger running tool with another orientation member lower through the BOP orientation spool and orient as they land in the inner wellhead housing. A production tree with an orientation member on a lower end lands on the inner wellhead housing. The orientation member of the production tree engages the orientation member of the tubing hanger to rotate the tree to a desired orientation.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to provisional application 60/425,377, filed Nov. 12, 2002.

BACKGROUND OF THE INVENTION

Subsea field development wells are often drilled in a pattern that spaces the wells apart from each other. Some wells, particularly those in deeper water have production trees that connect to flowlines or jumpers that extend along the sea floor. The flowline jumpers lead to manifolds and/or to other subsea production trees. The flowline connector for each tree is often configured horizontal and off to one side of the tree.

When developing the field, the operator orients the trees to align with the flowline connectors. The operator typically precisely measures the various distances from connector to connector and prefabricates the jumpers. Sometimes after some of the wells have been drilled, plans change. The relative bearings between wells to be drilled may not be the same as originally anticipated. A change in plans may require reconfigured jumpers to match the revised placement of manifolds.

A typical subsea wellhead assembly has a high pressure wellhead housing supported in a low pressure wellhead housing and secured to casing that extends into the well. One or more casing hangers land in the high pressure wellhead housing, each casing hanger being located at the upper end of a string of casing that extends into the well. A string of tubing extends through the casing for conveying production fluids. A Christmas or production tree mounts to the upper end of the wellhead housing for controlling the well fluid.

One type of tree, sometimes called “conventional” or “vertical”, has two bores through it, one of which is the production bore and the other being the tubing annulus access bore. In this type of wellhead assembly, the tubing hanger lands in the high pressure wellhead housing. The tubing hanger has two passages through it, one being the production passage and the other being an annulus passage that communicates with the tubing annulus surrounding the tubing. Access to the tubing annulus is necessary, both to monitor and bleed down pressure during production and to circulate fluids down the production tubing and up through the tubing annulus, or vice versa, to either kill the well or circulate out heavy fluid during completion. The tree has isolation tubes that stab into engagement with the passages in the tubing hanger when the tree lands on the wellhead housing.

The tubing hanger for a conventional tree must be oriented in a desired direction before the tree is run. In this type of wellhead assembly, the low and high pressure wellheads are not oriented. Rather orientation is handled by running the BOP (blowout preventer) assembly on guidelines that orient the BOP to a guide base that supports the low pressure wellhead housing. The flowline connector is located on the guide base and fixed in a particular direction. The BOP assembly has an orientation pin within it. The tubing hanger has an orientation member that engages the internal orientation member of the BOP to orient the tubing hanger. The tree is also coarsely oriented typically by guidelines for aligning with the previously oriented tubing hanger, providing one tolerance path from the guidebase, via the BOP stack to the tubing hanger, and another from the guidebase to the tree, which must be accounted for.

In another type of tree, sometimes called “horizontal” tree, there is only a single bore in the tree, this being the production passage. The tubing hanger lands in the tree rather than in the high pressure wellhead housing. Neither the high nor the low pressure wellhead housing are oriented. The tree is oriented as it is lowered on the high pressure wellhead housing. The tubing hanger has a lateral port that requires orientation, thus it engages an orientation member in the tree as it is installed.

Flexibility within the installation of the overall subsea system (i.e. tree, flowline jumpers and manifolds) is desired for orienting trees in systems that locate the tubing hanger in the high pressure wellhead housing. For example, it would be useful to be able to change flowline connector orientation after the well has been drilled and cased, but before running the tubing hanger.

SUMMARY OF THE INVENTION

In this invention, the well is drilled and cased through a wellhead housing. A string of tubing is run through the wellhead, with the tubing hanger landing in the wellhead housing in a desired rotational orientation. Also, the tubing hanger has an orientation member on an upper end. A production tree with an orientation member on a lower end lands on the wellhead housing, thereby engaging the orientation member of the tubing hanger to rotate the tree to a desired orientation.

Preferably, the wellhead housing lands in a supporting wellhead, the supporting wellhead being previously oriented in a desired orientation and having an external orientation member. Also, preferably, prior to running the tubing, a BOP orientation spool is lowered onto the wellhead housing, the BOP orientation spool having an orientation member within. The tubing hanger passes through the BOP orientation spool and orients with the orientation member in the BOP orientation spool. The BOP orientation spool is then removed and the tree installed on the wellhead housing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B comprise a vertical sectional view of a wellhead assembly constructed in accordance with this invention.

FIG. 2 is an enlarged sectional view of a portion of the wellhead assembly of FIGS. 1A and 1B, the sectional plane being different than in FIGS. 1A and 1B.

FIG. 3 is an enlarged sectional view of a portion of the wellhead assembly of FIGS. 1A and 1B.

FIG. 4 is an another sectional view of a portion of the wellhead assembly of FIGS. 1A and 1B, but shown in same sectional plane as in FIG. 2 to illustrate a tubing annulus valve in a closed position.

FIG. 5 is an enlarged sectional view of the tubing annulus valve of FIG. 4, shown in an open position and engaged by an engaging member of the production tree.

FIG. 6 is an enlarged sectional view of the tubing annulus valve of FIG. 4, shown in a closed position while a tubing hanger running tool is being connected to the tubing hanger.

FIG. 7 is a sectional view of the tubing annulus valve as shown in FIG. 6, but shown in an open position.

FIG. 8 is a sectional view of the wellhead housing of the wellhead assembly of FIGS. 1A and 1B after running casing and in the process of receiving a BOP orientation spool.

FIG. 9 is a schematic horizontal sectional view of the wellhead housing of FIG. 8, the dotted lines showing a flowline connector arm being rotated.

FIG. 10 is a perspective view of the wellhead assembly of FIGS. 1A and 1B, after the BOP orientation spool of FIG. 8 has landed.

FIG. 11 is a schematic vertical sectional view of the wellhead assembly of FIGS. 1A and 1B, showing an ROV deployed plug tool mounted on the tree.

FIG. 12 is a schematic side view of the plug tool of FIG. 11, with a plug setting attachment.

FIG. 13 is a schematic sectional view of a plug retrieving attachment for the plug tool of FIG. 11, shown in a disengaged position with a plug illustrated by the dotted lines.

FIG. 14 is a more detailed sectional view of the plug retrieving attachment of FIG. 13, shown in an engaged position.

FIG. 15 is a schematic view of a drilling platform in engagement with one subsea wellhead assembly, while a lift line on the platform is in engagement with another subsea wellhead assembly.

FIG. 16 is a vertical sectional view of an alternate embodiment of the portion of the tree of FIGS. 1A and 1B that connects to the inner wellhead housing.

FIG. 17 is a perspective view of the wellhead assembly of FIGS. 1A and 1B, with a tree installed thereon.

FIG. 18 is an enlarged perspective view of one connector of a flowline jumper for connecting to the tree of FIG. 1.

FIG. 19 is a perspective view of the flowline jumper of FIG. 18.

FIG. 20 is a schematic view of the flowline jumper of FIG. 18, shown being lowered into the sea.

FIG. 21 is a schematic view of the flowline jumper of FIG. 18, shown being stabbed into the tree flowline connector.

FIG. 22 is a schematic view of the flowline jumper of FIG. 18, showing a remote operated vehicle in the process of connecting to the flowline jumper.

FIG. 23 is a schematic view of the flowline jumper of FIG. 18, showing the ROV landed on a subsea manifold and connected by a pull line to the flowline jumper.

FIG. 24 is a schematic view of the flowline jumper of FIG. 18, showing the pull line being retracted by the ROV, drawing the second connector of the flowline jumper into alignment with the manifold.

FIG. 25 is a schematic view of the flowline jumper of FIG. 18, showing the second connector of the flowline jumper being connected to the subsea manifold.

FIG. 26 is a schematic view of the flowline jumper of FIG. 18, showing the remote operated vehicle connecting the couplings of the flowline jumper and the tree to each other.

FIG. 27 is a schematic view of the flowline jumper of FIG. 18, showing the installation completed and the ROV being retrieved.

FIG. 28 is a schematic view of an alternate embodiment of a flowline jumper.

DETAILED DESCRIPTION OF THE INVENTION

Overall Structure of Subsea Wellhead Assembly

Referring to FIG. 1B, a lower portion of a wellhead assembly 11 includes an outer or low pressure wellhead housing 13 that locates on the sea floor and is secured to a string of large diameter conductor pipe 15 that extends into the well. In this embodiment, a first string of casing 17 is suspended on a lower end of outer wellhead housing 13 by a hanger 19. However, casing 17 and hanger 19 are not always suspended from the outer wellhead housing 13 and can be eliminated in many cases.

An inner or high pressure wellhead housing 21 lands in and is supported within the bore of outer wellhead housing 13. Inner wellhead housing 21 is located at the upper end of a string of casing 23 that extends through casing 17 to a greater depth. Inner wellhead housing 21 has a bore 25 with at least one casing hanger 27 located therein. Casing hanger 27 is sealed within bore 25 and secured to the upper end of a string of casing 29 that extends through casing 23 to a greater depth. Casing hanger 27 has a load shoulder 28 located within its bore or bowl.

In this embodiment, a tubing hanger 31 is landed, locked, and sealed within the bore of casing hanger 27. Referring to FIG. 2, tubing hanger 31 has a lower end that lands on load shoulder 28. A seal 30 seals between the exterior of tubing hanger 31 and the bore of casing hanger 27 above load shoulder 28. A split lock ring 34 moves from a retracted position radially outward to lock tubing hanger 31 to an internal profile in casing hanger 27, or alternatively may lock into the bore of the high pressure housing 21, or an adapter bowl located in the high pressure housing. A sleeve 36, when moved axially downward, energizes seal 30 as well as pushes lock ring 34 to the locked position. Tubing hanger 31 is secured to the upper end of a string of production tubing 33. Tubing hanger 31 has a production passage 32 that is coaxial with tubing 33.

Referring to FIG. 3, inner wellhead housing bore 25 has a lower portion 25 a that has a smaller diameter than upper portion 25 b. The difference in diameters results in a conical generally upward facing transition portion or shoulder 25 c located between portions 25 a and 25 b. Wellhead housing bore upper portion 25 b has a grooved profile 35 formed therein above tubing hanger 31. Profile 35 is located a short distance below rim 37, which is the upper end of inner wellhead housing 21.

As shown in FIG. 1A, a Christmas or production tree 39 has a lower portion that inserts into wellhead housing 21. Production tree 39 has a production passage 41 extending through it that has an outlet port 41 a extending laterally outward. Production tree 39 has an isolation tube 43 that depends downward from its lower end and stabs sealingly into production passage 32 of tubing hanger 31. The lower end of production tree 39 extends into bore 25 of inner wellhead housing 21 to bore transition section 25 c (FIG. 3).

Referring again to FIG. 3, an orientation sleeve 44 is a part of and extends upward from tubing hanger 31. Orientation sleeve 44 is nonrotatably mounted to the exterior of the body of tubing hanger 31. Orientation sleeve 44 has a helical contour formed on its upper edge. A mating orientation sleeve 46 with a helical contour on its lower edge is secured to the lower end of production tree 39. When tree 39 is lowered into wellhead housing 21, orientation sleeve 46 engages the helical contour of orientation sleeve 46 to rotate production tree 39 and finally orient it in the desired direction relative to tubing hanger 31. The capture range of the helical interface directly affects the height of the orientation helix. In order to minimize the effect of this onto the system, the tree can be nominally pre-aligned via a supplementary mechanical register, via the structural sub-frame 133. This is achieved in the same manner, typified by a pin to funnel arrangement, as that described later for registering the correct orientation of a BOP orientation spool.

Tree and Wellhead Housing Internal Connector

Tree 39 includes a connector assembly for securing it to wellhead housing 21. The connector assembly includes a connector body 45 that has a downward facing shoulder 47 that lands on rim 37. Connector body 45 is rigidly attached to tree 39. A seal 49 seals between rim 37 and shoulder 47. Connector body 45 also extends downward into wellhead housing 21. A locking element 51 is located at the lower end of connector body 45 for engaging profile 35. Locking element 51 could be of a variety of types. In this embodiment, locking element 51 comprises an outer split ring that has a mating profile to groove 35. A plurality of dogs 53 located on the inner diameter of locking element 51 push locking element 51 radially outward when moved by a cam sleeve 55. Cam sleeve 55 moves axially and is hydraulically driven by hydraulic fluid supplied to a piston 57, or else by rods connected to externally mounted hydraulic cylinders.

The connector assembly has an extended or retainer portion 59 that extends downward from connector body 45 in this embodiment. Extended portion 59 is located above and secured to orientation sleeve 44. A collar 60 is threaded to the outer diameter of extended portion 59 for retaining locking element 51 and dogs 53 with connector body 45. Alternately dogs 53 could be used to engage profile 35 and locking element 51 omitted. In that case, windows could be provided for the dogs in connector body 45, and extended portion 59 and collar 60 would be integrally formed with connector body 45.

Referring to FIG. 1A, a control fluid passage 61 extends through tree 39 to an exterior side portion for supplying control fluid. Although not shown, there are a number of these passages, and they lead to connector tubes on the lower end of tree 39. The connector tubes stab into mating passages on the upper end of tubing hanger 31. These passages lead to hydraulic and/or electrical control lines that are not shown but extend below tubing hanger 31 on the outside of production tubing 33. These control lines lead to downhole equipment in the string of tubing 33, such as a downhole safety valve and downhole pressure and temperature monitoring devices.

At least one valve is mounted to production tree 39 for controlling fluid flow. In the preferred embodiment, the valves include a master valve 63 and a swab valve 65 located in production passage 41. A safety shutoff valve 67 is mounted to port 41 a. The hydraulic actuator 68 for safety shutoff valve 67 is shown. Valves 63 and 65 may be either hydraulically actuated or mechanically actuated (typically by ROV).

Referring again to FIG. 1A, tree 39 has a mandrel 81 on its upper end that protrudes upward. Mandrel 81 is typically sized for receiving a connector for connection to a small diameter, lightweight riser, such as for certain workover purposes. Mandrel 81 also enables other methods of intervention.

Tubing Annulus Access

FIG. 4 illustrates a tubing annulus passage 83, which is not shown in FIG. 1B or 3 because tubing annulus passage 83 is located in a different vertical sectional plane than that shown in FIGS. 1B and 3. Tubing annulus passage 83 extends vertically through tubing hanger 31 from an upper end portion to a lower end, where it communicates with a tubing annulus 85 surrounding tubing 33. The upper and lower ends of tubing annulus passage 83 may be slightly radially offset from each other, as shown in FIG. 4. An annular void space 87 surrounds isolation tube 43 between the upper end of tubing hanger 31 and the lower end of tree 39.

A tubing annulus valve 89 is mounted in tubing annulus passage 83 to block tubing annulus passage 83 from flow in either direction when closed. Referring to FIG. 5, tubing annulus valve 89 has a stem base 91 that is secured by threads 93 to tubing annulus passage 83. A stem 95 extends upward from stem base 91 along the axis of tubing annulus passage 83. An enlarged valve head 97 forms the upper end of stem 95. Valve head 97 has a secondary resilient seal as well as a primary lip seal 99 made of metal in this embodiment.

A shuttle sleeve 101 is reciprocally carried in tubing annulus passage 83. While in the upper closed position shown in FIGS. 4 and 6, the upper end of sleeve 101 is a short distance below an upper end portion of tubing hanger 31. While in the lower open position, shown in FIGS. 5 and 7, sleeve 101 is in a lower position relative to valve head 97. Sleeve 101 has a reduced diameter port or seat 103 formed in its interior. Seat 103 is sealingly engaged by lip seal 99 as well as the resilient seal of valve head 97 while sleeve 101 is in the lower position.

An outward biased split ring 105 is mounted to the outer diameter of sleeve 101 near its upper end. Split ring 105 has a downward tapered upper surface and a lower surface that is located in a plane perpendicular to the axis of tubing annulus passage 83. A mating groove 107 is engaged by split ring 105 while sleeve 101 is in the upper, closed position. Split ring 105 snaps into groove 107, operating as a detent or retainer to prevent downward movement of sleeve 101.

FIG. 5 shows an engaging tool or member 109 extending into the upper end of tubing annulus passage 83 into engagement with the upper end of sleeve 101. Engaging member 109 is a downward extending component of tree 39 (FIG. 1A) and is used for moving sleeve 101 from the upper to the lower position. A second identical engaging member 109′, shown in FIGS. 6 and 7, is mounted to a running tool 111 used to run tubing hanger 31. Engaging member 109 has a lip 113 on its lower end that mates with the upward facing taper on split ring 105. Lip 113 slides over and causes split ring 105 to contract, enabling engaging member 109 to push sleeve 101 downward to the open position. A spring 115, which may be a plurality of Belleville washers, is located between stem base 91 and the lower end of sleeve 101. Spring 115 urges sleeve 101 to the upper closed position. Any pressure in passage 83 would assist spring 155 in moving sleeve 101 to the closed position.

Engaging member 109 is secured to the lower end of an actuator 117, which is mounted in tree 39. Actuator 117 is a hollow, tubular member with open ends reciprocally carried in a tubing annulus passage 118 in tree 39 (FIG. 3). Actuator 117 has a piston portion on its exterior side wall that is selectively supplied with hydraulic fluid for moving actuator 117 between upper and lower positions. Tubing annulus passage 118 extends through tree 39 to an exterior side portion of tree 39 for connection to a tubing annulus line that leads typically to a subsea manifold or an umbilical that serves the tree. Tubing annulus passage in tree 118 does not extend axially to the upper end of tree 39.

When actuator 117 is moved to the lower position, engaging member 109 engages and pushes sleeve 101 from the closed position to the open position. FIGS. 6 and 7 show a similar actuator 117′ that forms a part of running tool 111 and works in the same manner as actuator 117. Like actuator 117, actuator 117′ has a piston portion that is carried in a hydraulic fluid chamber for causing the upward and downward movement in response to hydraulic pressure. Passage 118′ leads to an exterior upper portion of running tool 111 for delivering and receiving tubing annulus fluid.

Running tool 111 has conventional features for running tubing hanger 31, including setting a seal between tubing hanger 31 and bore 25 of wellhead housing 21 (FIG. 4). Running tool 111 has a lock member 119 that is radially and outwardly expansible into a mating groove formed in an interior upward extending sleeve portion of tubing hanger 31. Lock member 119 secures running tool 111 to tubing hanger 31 while tubing 33 is being lowered into the well. Lock member 119 is energized and released by a lock member actuator 121, which is also hydraulically driven. Running tool 111 has a sleeve 123 that slides sealingly into the bore 32 of tubing hanger 31. Sleeve 123 isolates the upper end of tubing annulus passage 83 from production passage 32 (FIG. 4) in tubing hanger 31.

Orientation

Referring to FIG. 8, a ring 125 is mounted to the exterior of outer wellhead housing 13, also referred to as a conductor housing. Ring 125 has a depending funnel 127 and is selectively rotatable on outer wellhead housing 13 for orienting tubing hanger 31 and tree 39 (FIG. 3) in a desired position relative to other subsea wells and equipment. A lock pin or screw 129 will selectively lock ring 125 in the desired position. An arm bracket 131 is mounted to ring 125 for rotation therewith. Arm bracket 131 cantilever supports a horizontally extending arm 133. Arm 133 has an upward facing socket on its outer end 131. Also, a mechanical register 137 protrudes upward from arm 133, depicted and typified by a pin.

Ring 125 is normally installed on outer wellhead housing 13 at the surface before outer wellhead housing 13 is lowered into the sea. Arm 133 will be attached to arm bracket 131 below the rig floor but at the surface. After outer wellhead housing 13 is installed at the sea floor, if necessary, an ROV may be employed later in the subsea construction phase to rotate ring 125 and/or arm 133, to a different orientation, typically towards a manifold connection point.

A BOP (blowout preventer) adapter 139 is being shown lowered over inner or high pressure housing 21. BOP orientation spool 139 is used to orient tubing hanger 31 (FIG. 3) relative to arm 133. BOP orientation spool 139 is preferably lowered on a lift line after the well has been drilled and casing hanger 27 installed. The drilling riser, along with the BOP, will have been removed from the upper end of inner wellhead housing 21 prior to lowering BOP orientation spool 139 in place. Alternatively, the BOP orientation spool may be deployed with the BOP and riser system, subject to rig handling limitations. BOP orientation spool 139 has a guide socket 143 that is mounted to its exterior at a point for aligning with pin 137. A funnel 141 on the lower end of BOP orientation spool 139 assists in guiding BOP orientation spool 139 over inner wellhead housing 21. Socket 143 will orient BOP orientation spool 139 to a position depending upon the orientation of arm 133 and pin 137. An ROV (not shown) will be used to assist guide socket 143 in aligning with guide pin 137.

BOP orientation spool 139 has a plurality of dogs 145 that are hydraulically energized to engage an external profile on inner wellhead housing 21. BOP orientation spool 139 also has seals (not shown) that seal its bore to bore 25 of wellhead housing 21. A helical orienting slot 147 is located within the bore of BOP orientation spool 139. Slot 147 is positioned to be engaged by a mating pin or lug on running tool 111 (FIG. 6) for tubing hanger 31. This engagement causes running tool 111 to orient tubing hanger 31 in a desired orientation relative to the orientation of arm 133. Alternatively, a radially actuated pin (operated via mechanical or hydraulic means, using an ROV) is mounted within the BOP orientation spool, that engages with a helix on the tubing hanger running tool. One example of why this alternative method may be used, would be the use of a “slim” tubing hanger (typically 13⅝″ nom. OD) inside a traditional 18 3/46″ BOP and riser system, such that the “reach” of the pin/lug of the tubing hanger running tool would be unable to bridge the gap.

FIG. 10 is a perspective view showing BOP orientation spool 139 in position on inner wellhead housing 21, which is not shown in FIG. 10 because it is located within the bore of BOP orientation spool 139. BOP orientation spool 139 has an upper end with a mandrel 146. The drilling riser and BOP will connect to the external profile on mandrel 146 after BOP orientation spool 139 has been connected to inner wellhead housing 21, unless the BOP orientation spool is deployed via the BOP and riser system.

Once BOP orientation spool 139 has oriented tubing hanger 31 (FIG. 1B), the well will typically be perforated and tested. Tubing hanger 31 must be oriented relative to the arm 133 because orientation sleeve 44 (FIG. 3) of tubing hanger 31 provides final orientation to tree 39, as shown in FIGS. 1A and 1B. Tree 39 has a tree funnel 148 that slides over inner wellhead housing 21 as it is landing.

The safety shutoff valve 67 of tree 39 is connected to a flow line loop 149 that leads around tree 39 to a flow line connector 151 on the opposite side as shown in FIG. 1B. Flow line connector 151 will connect to a flow line 153 that typically leads to a manifold or subsea processing equipment. In this embodiment, flow line 153 is mounted to a vertical guide pin or mandrel 155 that stabs into guide funnel 135 to orient to tree 39. Other types of connections to flow line connector 151 could also be employed. Consequently, tree is oriented so that its flowline connector 151 will register with flowline 153.

Plug Retrieval and Installation

After tree 39 is installed, a plug 159 (FIG. 12) must be removed from a plug profile 157 located within tubing hanger 31, as shown in FIG. 11. Plug 159 maintains pressure that is within tubing 33 after BOP orientation spool 139 (FIG. 10) is removed and prior to installing tree 39 (FIG. 1A). Plug 159 is conventional and has one or more seals 161 that seal within production passage 41 of tubing hanger 31. Plug 159 has a plurality of locking elements 163 that will move radially outward between a retracted and an extended position. Locking elements 163 engage a mating groove in profile 157.

Preferably, rather than utilizing wireline inside a workover riser, as is typical, an ROV deployed plug tool 165 is utilized. Plug tool 165 does not have a riser extending to the surface, rather it is lowered on a lift line. Plug tool 165 has a hydraulic or mechanical stab 167 for engagement by ROV 169. Plug tool 165 lands on top of tree mandrel 81. A seal retained in plug tool 165 engages a pocket in mandrel 81 of tree 39. When supplied with hydraulic pressure or mechanical movement from ROV 169, a connector 171 will engage mandrel 81 of tree 39. Similarly, connector 171 can be retracted by hydraulic pressure or mechanical movement supplied from ROV 169.

Plug tool 165 has an axially movable stem 173 that is operated by hydraulic pressure supplied to a hydraulic stab 174. A retrieving tool 175 is located on the lower end of stem 173 for retrieving plug 159. Similarly, a setting tool 177 may be attached to stem 173 for setting plug 159 in the event of a workover that requires removal of tree 39. Setting tool 177 may be of a variety of types and for illustration of the principle, is shown connected by shear pin 179 to plug 159. Once locking elements 163 have engaged profile 157, an upward pull on stem 173 causes shear pin 179 to shear, leaving plug 159 in place.

Retrieving tool 175, shown in FIGS. 13 and 14, may also be of a variety of conventional types. In this embodiment, retrieving tool 175 has a body 181 that inserts partially into a receptacle 183 in plug 159. A locator sleeve 185 on the exterior of body 181 will land on the rim of receptacle 183. A collet 187 is located within locator sleeve 185 and protrudes below a selected distance. When locator sleeve 185 has landed on the rim of plug 159, collet 187 will be aligned with a groove 189 within the plug 159.

Collet 187 and sleeve 185 are joined to a piston 191. Piston 191 is supplied with hydraulic fluid from ROV 169 (FIG. 10) via one of the stabs 174. A spring 193 is compressed while retrieving tool 175 is in the released position, shown in FIG. 13. Spring 193 urges piston 191 to a lower position. When hydraulic pressure is relieved at passage 192, spring 193 will cause body 181 to move upward to the position shown in FIG. 14. In this position, a wall portion 194 of body 181 will locate directly radially inward of collet 187, preventing collet 187 from disengaging from profile 189. Once retrieving tool 175 is attached to plug 159, ROV 169 will actuate one of the hydraulic stabs or mechanical interfaces 174 to cause stem 173 (FIG. 11) to move upward. Collet 187 causes dogs 163 to be radially retractable during this upward movement as plug 159 is disengaged. Once plug 159 is above tree valve 65, tree valve 65 may be closed, enabling the entire assembly of plug tool 165 to be retrieved to the surface with a lift line.

Field Development

FIG. 16 schematically illustrates a preferred method for developing a field having a plurality of closely spaced wellhead assemblies 11. This method is particularly useful in water that is sufficiently deep such that a floating platform 195 must be utilized. Platform 195 will be maintained in position over the wells by various conventional means, such as thrusters or moorings. Platform 195 has a derrick 197 with a drawworks 199 for drilling and performing certain operations on the wells. Platform 195 also has a drilling riser 201 that is employed for drilling and casing the wells. Drilling riser 201 is shown connected to high pressure housing 21 of one wellhead assembly 11. Drilling riser 201 has a blowout preventer 203 within it. In the particular operation shown, a string of drill pipe 205 is shown extending through riser 201 into the well.

Platform 195 also preferably has a crane or lift line winch 207 for deploying a lift line 209. Lift line 207 is located near one side of platform 195 while derrick 197 is normally located in the center. Optionally, lift line winch 207 could be located on another vessel that typically would not have a derrick 197. In FIG. 14, a tree 39 is shown being lowered on lift line 209.

Drilling and Completion Operation

In operation, referring to FIG. 8, outer housing 13 along with ring 125 and arm 133 are lowered into the sea. Outer housing 13 is located at the upper end of conductor 15, which is jetted into the earth to form the first portion of the well. As conductor 15 nears the seabed, the entire assembly and arm 133 will be set in the desired position. This position will be selected based on which way the field is to be developed in regard to other wells, manifolds, subsea processing equipment and the like. Once conductor 15 has been jetted into place and later in the subsea construction program, the operator may release lock pins 129 and rotate ring 125 to position arm 133 in a different orientation. This subsequent repositioning of arm 133 is performed as necessary or as field development needs change to optimize connection points for the well flowline jumpers.

The operator then drills the well to a deeper depth and installs casing 117, if such casing is being utilized. Casing 117 will be cemented in the well. The operator then drills to a deeper depth and lowers casing 23 into the well. Casing 23 and high pressure wellhead housing 21 are run on drill pipe and cemented in place. No orientation is needed for inner wellhead housing 21. The operator may then perform the same steps for two or three adjacent wells by repositioning the drilling platform 195 (FIG. 15).

The operator connects riser 201 (FIG. 15) to inner wellhead housing 21 and drills through riser 201 to the total depth. The operator then installs casing 29, which is supported by casing hanger 27. In some cases, an additional string of casing would be installed with the well being drilled to an even greater depth.

The operator is then in position to install tubing hanger 31 (FIG. 1B). First, the operator disconnects drilling riser 201 (FIG. 15) and BOP 203 and suspends it off to one side of wellhead assembly 11. The operator lowers BOP orientation spool 139 on lift line 209 over inner wellhead housing 21, as illustrated in FIG. 8. With the aid of an ROV, socket 143 is positioned to align with pin 137. BOP orientation spool 139 is locked and sealed to inner wellhead housing 21. BOP orientation spool 139 may have been previously installed on an adjacent well left temporarily abandoned.

The operator then attaches drilling riser 201, including BOP 203, (FIG. 15) to mandrel 146 (FIG. 10) of BOP orientation spool 139. The operator lowers tubing 33 and tubing hanger 31 through drilling riser 201 on running tool 111 (FIG. 6), which is attached to a tubing hanger running string, which is a small diameter riser. Once running tool 111 is connected to tubing hanger 31, actuator 117′ is preferably stroked to move engaging member 109′ downward, thereby causing shuttle sleeve 101 to move downward. This opens tubing annulus passage 83 for upward and downward flow. Running tool 111 has a retractable pin (not shown) that engages BOP orientation spool guide slot 147 (FIG. 8), causing it to rotate tubing hanger 31 to the desired position as it lands within casing hanger 27. Alternatively, the pin mounted on the BOP orientation spool is actuated by ROV to engage the tubing hanger running tool.

After tubing hanger 31 has been set, the operator may test the annulus valve 89 by stroking actuator 117′ upward, disengaging engaging member 109 from sleeve 101 as shown in FIG. 6. Spring 115 pushes sleeve 101 to the upper closed position. In this position, valve head seal 99 will be engaging sleeve seat 103, blocking flow in either the upward or downward direction. While in the upper position, detent split ring 105 engages groove 107, preventing any downward movement.

The operator then applies fluid pressure to passage 118′ within running tool 111. This may be done by closing the blowout preventer in drilling riser 201 on the small diameter riser above running tool 111. The upper end of passage 118′ communicates with an annular space surrounding the small diameter riser below the blowout preventer in drilling riser 201. This annular space is also in communication with one of the choke and kill lines of drilling riser 201. The operator pumps fluid down the choke and kill line, which flows down passage 118′ and acts against sleeve 101. Split ring 105 prevents shuttle sleeve 101 from moving downward, allowing the operator to determine whether or not seals 99 on valve head 97 are leaking.

The well may then be perforated and completed in a conventional manner. In one technique, this is done prior to installing tree 39 by lowering a perforating gun (not shown) through the small diameter riser in the drilling riser 201 (FIG. 15) and through tubing 33. The smaller diameter riser may optionally include a subsea test tree that extends through the drilling riser.

If desired, the operator may circulate out heavy fluid contained in the well before perforating. This may be done by opening tubing annulus valve 89 by stroking actuator 117′ and engaging member 109′ downward. Engaging member 109′ releases split ring 105 from groove 107 and pushes sleeve 101 downward to the open position of FIG. 7. A port such as a sliding sleeve (not shown) at the lower end of tubing 33 is conventionally opened and the blowout preventer in drilling riser 201 is closed around the tubing hanger running string. The operator may circulate down the running string and tubing 33, with the flow returning up tubing annulus 85 into drilling riser 201 and up a choke and kill line. Reverse circulation could also be performed.

After perforating and testing, the operator will set plug 159 (FIG. 12) in profile 157 (FIG. 11) in tubing hanger production passage 32. Tubing annulus valve 89 is closed to the position of FIG. 6 by stroking actuator 117′ upward, causing spring 115 to move sleeve 101 upward. The operator then retrieves running tool 111 on the running string through the blowout preventer and drilling riser 201. The downhole safety valve (not shown) in tubing 33 is above the perforations and is preferably closed to provide a first pressure barrier; plug 159 in tubing hanger production passage 32 providing a second pressure barrier. Tubing annulus 85 normally would have no pressure, and tubing annulus valve 89 provides a second (temporary) barrier in addition to the primary barriers to wellbore pressure, these being the production tubing itself and the production packer in the tubing completion system.

The operator then retrieves running tool 111 (FIG. 6) on the small diameter riser. The operator releases drilling riser 201 and BOP 203 from BOP orientation spool 139 (FIG. 8) and retrieves BOP orientation spool 139 on lift line 209 (FIG. 15) or deploys BOP orientation spool 139 on an adjacent well. The operator may then skid platform 195 sequentially over the other wells for performing the same functions with BOP orientation spool 139 and drilling riser 201 for a different well. Once tubing 29 has been run and perforated on a particular well, there is no more need for drilling riser 201 or derrick 197 (FIG. 15) at that location. Even though platform 195 may have skidded out of alignment with the particular well (as an example, to continue operations on an adjacent well location), an ROV can guide lift line 209 down to engage BOP orientation spool 139 in order to enable recovery to surface or else movement to yet another adjacent well, within working proximity.

The operator is now in position for running tree 39 on lift line 209 (FIG. 15). Tree 39 orients to the desired position by the final engagement of the orienting members 44 and 46 (FIG. 3). This positions tree connector 151 in alignment with flowline connector 153, if such had already been installed, or at least in alignment with socket 127. Flowline connector 153 could be installed after installation of tree 39, or much earlier, even before the running of high pressure wellhead housing 21. As tree 39 lands in wellhead housing 21, its lower end will move into bore 25 of wellhead housing 21, and isolation tube 43 will stab into production passage 32 of tubing hanger 31. While being lowered, orientation member 44 engages orientation sleeve 46 to properly orient tree 39 relative to tubing hanger 31. Once landed, the operator supplies hydraulic fluid pressure to cam sleeve 55, causing dogs 53 to push locking element 51 (FIG. 2) to the outer engaged position with profile 35. Flowline connector 151 (FIG. 1B) of tree 39 aligns with flowline connector 153, and the tubing annulus passage (not shown) in tree 39 is connected to a manifold or a related facility.

Referring to FIGS. 11–13, in a preferred technique, with lift line 209 (FIG. 15) and the assistance of ROV 169, the operator connects plug tool 165 to tree mandrel 81 and removes plug 159 in tubing hanger 31 with retrieval tool 175. Tree valve 65 is closed once plug 159 is above it. Plug tool 165 may be retrieved and a tree cap installed, typically using ROV 169. Tree 39 should be ready for production.

Referring to FIG. 5, during production, tubing annulus valve 89 may remain closed, but is typically held open for monitoring the pressure in tubing annulus 85. If tubing annulus valve 89 is closed, it can be opened at any time by stroking actuator 117 (FIG. 5) of tree 39 downward. Any pressure within tubing annulus 85 is communicated through tubing annulus passage 118 in tree 39 and to a monitoring and bleedoff facility.

For a workover operation that does not involve pulling tubing 33, a light weight riser with blowout preventer may be secured to tree mandrel 81. An umbilical line would typically connect the tubing annulus passage on tree 39 to the surface vessel. Wireline tools may be lowered through the riser, tree passage 41 and tubing 33. The well may be killed by stroking actuator 117 (FIG. 5) downward to open tubing annulus valve 89. Circulation can be made by pumping down the riser, through tubing 33, and from a lower port in tubing 33 to tubing annulus 85. The fluid returns through tubing annulus passage 83 and passage 118 in tree 39 to the umbilical line.

For workover operations that require pulling tubing 33, tree 39 must be removed from wellhead housing 21. A lightweight riser would not be required if tubing hanger plug 159 (FIG. 12) is reset into profile 157 of tubing hanger 31 with plug tool 165 (FIG. 11). The operator installs plug tool 165 using lift line 209 (FIG. 15) and ROV 169. Plug 159 is attached to stem 173 and retrieval tool 177 and lowered into profile 157. Once locking elements 163 latch into profile 157, the retrieval tool 177 is released from plug 159. The downhole safety valve in tubing 33 typically would be closed during this operation. Tree 39 is retrieved on lift line 209 with the assistance of ROV 169. Then, drilling riser 201 (FIG. 15) is lowered into engagement with inner wellhead housing 21. The operator retrieves tubing 33 and performs the workover in a conventional manner.

Alternate Embodiment

FIG. 16 shows an alternate embodiment for the internal connector portions of a tree 210. Tree 210 is the same as tree 39, but for its connecting mechanism. Tree 210 has a plurality of dogs 211 that move radially inward and outward between retracted and extended positions. Dogs 211 engage an internal profile 213 located within the bore of wellhead housing 214. A cam 215, when moved axially upward, causes dogs 211 to move radially outward.

Cam 215 is secured to a plurality of rods 217. Rods 217 lead to an annular piston 219. or else a plurality of hydraulic cylinders externally mounted. Piston 219 has a lock chamber 22 that causes it to move upward when supplied with hydraulic fluid pressure, moving cam 215 to the upper position. Piston 219 also has an unlocking chamber 223. When supplied with hydraulic fluid pressure, the pressure in unlocking chamber 223 forces piston 219 downward to free dogs 211 to retract. Preferably the taper between cam 215 and dogs 211 is a locking taper so that cam 215 will not move downward if hydraulic pressure fails.

Flowline Jumpers

FIG. 17 shows tree 39 installed, tree 39 typically having a control assembly 225 mounted to it for controlling various valves (not shown) mounted to the tree. Alternately, the control of the various valves may be handled in a control center separate from tree 39. The valves control the flow of fluids within and from tree 39. Flowline coupling 153 is aligned in position to mate with tree coupling 151. Couplings 153, 151 may be of variety of types including collet, clamp, flange or other types. Flowline coupling 153 is mounted to one end of a flowline jumper 226. Tree flowline connector 151 will have been previously oriented in a desired direction as discussed in connection with FIGS. 8 and 9.

Mandrel 155 extends from flowline coupling 153 for reception within socket 135. Mandrel 155 positions flowline coupling 153 in alignment with tree coupling 151 when jumper 226 is lowered into the sea from the surface. As shown also in FIG. 18, a hinge mechanism 227 connects flowline coupling 153 and mandrel 155 to flowline jumper 226. Hinge mechanism 227 allows flowline jumper 226 to move to a position parallel to mandrel 155, as illustrated by the dotted lines. In the connected position, coupling 153 is 90° relative to mandrel 155. Hinge mechanism 227 may be of a variety of types, and in this embodiment, hinge mechanism 226 comprises a clevis and a pair of pins 229 that rotate within holes in the clevis.

Referring to FIG. 19, flowline jumper 226 may be a single integral conduit or a number of sections secured together, such as by threads, flanged ends, or welding. Flowline jumper 226 may be of carbon steel along with a number of other alloys such as titanium and chrome. Flowline jumper 226 may also be formed at least partially of composite materials such as fiber in a resin. Flowline jumper 226 may be pre-bent into an arcuate configuration or it may be sufficiently flexibly to curve into the arcuate configuration when lowered. Furthermore, flowline jumper 226 could be formed of flexible pipes that are made of multiple articulated components that flex relative to each other. Flowline jumper 226 may have a single passage through it or multiple passages.

Flowline jumper 226 also has at least a portion that is buoyant. In this embodiment, a plurality of short buoyant segments 231 are secured over flowline jumper 226, forming a buoyant jacket. As shown in FIG. 19, segments 231 need not extend the full length of flowline jumper 226. However, they should extend sufficiently to cause the arcuate central section to float in a vertical plane. If not pre-bent into an arcuate shape, the length of flowline jumper 226 relative to its diameter will cause a portion to flex into an arcuate shape due to buoyancy even if the conduit of flowline jumper 226 is of steel. The flexibility of flowline jumper 226 is preferably sufficient to avoid any permanent deformation due to the buoyancy of buoyant members 231. The buoyancy should be adequate to provide buoyancy to the arcuate portion of jumper 226 whether filled with water, hydrocarbon liquid or gas. Segments 231 may serve as bend restrictors to prevent excessive bending of the conduit of flowline jumper 226.

A vertical connector 233 is located on the end opposite connector 153. Connectors 233 and 153 are preferably negatively buoyant for ease in installation. Connector 233, like connector 153, may be of a variety of types. When flowline jumper 226 is installed, a portion extending from connector 153 will be horizontal and a portion extending from vertical connector 233 will be vertical. Buoyant members 231 cause the curved portion adjacent vertical connector 233 to extend upward within a vertical plane. The combination of the horizontal portion and arcuate portion over the length of jumper 226 may be termed a lazy wave.

FIGS. 20–27 illustrate one method for connecting wellhead assembly 11 to a second component, which in this case is a subsea manifold 235. The same method could be used for connecting manifold 235 to other subsea components, such as a subsea fluid processing unit. The second component 235 could also be another flowline, or a daisy chain to another well. Manifold 235 receives flow from a number of subsea wells and routes that flow to further processing equipment. The second component 235 could include such equipment normally mounted to tree 39 (FIG. 1A), such as a choke, production/injection flow isolation valve, multi-phase flow meters, erosion monitoring, corrosion monitoring and pressure and temperature monitoring. The connection of flowline jumper 226 to subsea wellhead assembly 11 could occur any time after running of low pressure wellhead housing 13.

The length of jumper 226 is greater than the horizontal distance between wellhead assembly 11 and manifold 235. The additional length is sufficient for the lazy wave configuration shown in FIGS. 19 and 27, however the precise configuration and the additional length of jumper 226 over the actual horizontal distance is not critical. The distances between wellhead assembly 11 and manifold 235 may vary and could be typically as short as 30 meters and as long as several kilometers.

As shown in FIG. 20, lift line 209 is secured to one of the ends of flowline jumper 226. In this embodiment, it is shown secured to second connector 233. The negative buoyancy of first connector 153 has caused it to assume a lower elevation than any other portion of jumper 23 as it is being lowered. Also, the negative buoyancy has caused mandrel 155 to hinge over to an orientation parallel with flowline jumper 226. Flowline jumper 226 is essentially straight and vertical in the positions of FIGS. 20–23.

In FIG. 21, mandrel 155 (FIG. 17) is shown stabbing into socket 135 while lift line 209 is still attached. Remote cameras may be used for guiding mandrel 155 into socket 135. Referring to FIG. 22, while flowline jumper 226 is still vertical, an ROV 237 is shown optionally attaching a pull line 239 to vertical connector 233. As shown in FIG. 23, ROV 237 reels out pull line 239 and lands on manifold 237. Lift line 209 still maintains flowline jumper 226 in the vertical orientation in FIG. 23. Then, as shown in FIG. 24, ROV 237 reels in pull line 239, causing second connector 233 to approach manifold 235, with lateral guidance where necessary. Hinge mechanism 227 (FIG. 18) allows first connector 153 and a portion of flowline jumper 226 to move to a horizontal position. FIG. 25 shows ROV 237 connecting second connector 233 to a suitable mandrel on manifold 235. Subsequently, as shown in FIG. 26, ROV 237 moves over into engagement with first connector 153. ROV 237 performs the actuation to cause first connector 153 to sealingly engage and secure to tree coupling 151 (FIG. 1A).

FIG. 27 illustrates flowline jumper 226 in the desired position, with lift line 209 removed and being retrieved as well as ROV 237. Buoyant members 231 (FIG. 19) cause the arcuate portion of flowline jumper 226 to float in a vertical plane after installation.

In the embodiment of FIG. 28, flowline jumper 241 may be constructed in the same manner as flowline jumper 226 (FIG. 19). It may contain a buoyant jacket (not shown) over all of its length or a portion. Both connectors 243, 245 are vertical types such as connector 233 (FIG. 19). Consequently, the buoyancy of flowline jumper 241 causes the single arcuate configuration to float in a vertical plane after installation.

The invention has significant advantages. The orientation system allows the operator to change the direction of the flowline connector up to the point that the tubing hanger is to be run. Rotating the flowline connector to a new direction may be readily done. Once rotated, the BOP orientation spool will automatically orient to the new direction. This assures that the tubing hanger will also orient to the new direction.

While the invention has been shown in only a few of its forms, it should be apparent to those skilled in the art that it is not so limited but is susceptible to various changes without departing from the scope of the invention. 

1. A method of drilling and completing a subsea well, comprising: (a) connecting a drilling riser to a wellhead housing and landing the wellhead housing in a supporting wellhead that has an external orientation member previously installed in a desired orientation; (b) drilling and casing a well through the wellhead housing; (c) disconnecting the drilling riser from the wellhead housing after casing has been installed; (d) landing a BOP orientation spool on the wellhead housing, the BOP orientation spool having an external orientation member that registers it to the external orientation member on the supporting wellhead, the BOP orientation spool having an internal orientation member; (e) connecting the drilling riser to the BOP orientation spool; and (f) providing a tubing hanger with an orientation member, connecting the tubing hanger to a string of tubing and running the tubing hanger through the drilling riser and BOP orientation spool and orienting the tubing hanger via the internal orientation member in the BOP orientation spool; (g) providing a production tree with an orientation member on a lower end; and (h) removing the BOP orientation spool from the wellhead housing, lowering the production tree onto the wellhead housing, and engaging the orientation member of the production tree with the orientation member of the tubing hanger to rotate the tree to a desired orientation.
 2. The method according to claim 1, wherein the tree is lowered onto the wellhead with a lift line.
 3. The method according to claim 1, further comprising: connecting the tree via a flowline jumper to additional subsea equipment, the flowline jumper having a portion with a curved configuration, the buoyancy causing the curved configuration portion to float in a vertical plane after installation.
 4. A method of drilling and completing a subsea well, comprising: (a) providing an outer wellhead housing with an external locator member and installing the outer wellhead housing at an upper end of a well and with the locator member in a desired orientation; (b) landing an inner wellhead housing in the outer wellhead housing; (c) drilling and casing the well through the inner wellhead housing; (d) then, if desired, re-orienting the locator member on the outer wellhead housing; (e) providing a BOP orientation spool that has an external orientation member and an internal orientation member; (f) lowering the BOP orientation spool onto the inner wellhead housing and engaging the external orientation member with the locator member to rotate and orient the BOP orientation spool; then (g) connecting a drilling riser to the BOP orientation spool; (h) providing a tubing hanger with an orientation member on its upper end, running the tubing hanger through the BOP orientation spool, the internal orientation member causing the tubing hanger to rotate and orient as the tubing hanger lands in the wellhead housing; then (i) disconnecting the BOP orientation spool and the drilling riser from the inner wellhead housing; and (j) providing a production tree with an orientation member on a lower end, lowering the production tree onto the inner wellhead housing, and engaging the orientation member of the production tree with the orientation member of the tubing hanger to rotate the tree to a desired orientation.
 5. The method according to claim 4, further comprising: mounting a flowline connector support to the outer wellhead housing, the support orienting in a desired orientation in step (a); mounting a flowline connector on the tree, which is oriented in alignment with the support in step (j); landing a flowline jumper on the support; and subsequently connecting the flowline connector to the flowline jumper after step (j).
 6. The method according to claim 4, wherein step (c) is performed through the drilling riser, and the method further comprises disconnecting the drilling riser before installing the BOP orientation spool.
 7. A subsea well assembly, comprising: a wellhead housing; a BOP orientation spool mounted on the wellhead housing in a desired orientation, the BOP orientation spool having an internal orientation member; a tubing hanger landed in the wellhead housing, the tubing hanger being oriented in a desired orientation by the internal orientation member of the BOP orientation spool while landing; an orientation member connected to an upper end of the tubing hanger; and a tree having an orientation member on a lower end that engages the orientation member of the tubing hanger while the tree is landing on the wellhead housing, causing the tree to rotate to a desired orientation.
 8. The assembly according to claim 7, wherein the orientation members comprise mating sleeves having matching helical or tapered contours.
 9. The assembly according to claim 7, further comprising a flowline connector mounted to the tree for rotating with the tree to the desired orientation.
 10. A subsea well assembly, comprising: a low pressure wellhead housing at an upper end of a well; a locator member and a flowline support mounted to the low pressure wellhead housing; a high pressure wellhead housing landed in the low pressure wellhead housing; a BOP orientation spool that mounts on an upper end of the high pressure wellhead housing; an external orientation member and an internal orientation member on the BOP orientation spool, the external orientation member engaging the locator member to register orientation of the BOP orientation spool while the BOP orientation spool lands on the high pressure wellhead housing; a tubing hanger having an orientation member on its upper end; a tubing hanger running tool connected to the tubing hanger, the tubing hanger running tool engaging the internal orientation member of the BOP orientation spool to cause the tubing hanger to rotate and orient while landing in the high pressure wellhead housing; and a production tree having a flowline connector and an orientation member on a lower end for engaging the orientation member of the tubing hanger to rotate the tree and the flowline connector to a desired orientation in alignment with the flowline support.
 11. The subsea well assembly according to claim 10, further comprising: a ring mounted to the low pressure wellhead housing to which the locator member and the flowline support are mounted enabling selective rotation of the locator member and flowline support relative to the low pressure wellhead housing. 